Crush preparation findings of "sarcomatoid" chordoma of the sacrum: report of a case with histologic, immunohistochemical, and ultrastructural correlation.

We report on the crush preparation findings of a case of "sarcomatoid" chordoma occurring in the sacral region of a 78-yr-old Chinese male. The smears showed clumps and small cords of polygonal tumor cells containing bubbly cytoplasm and round to oval nuclei. Focally, there were also aggregates of long filamentous spindle cells and stellate bizarre cells with marked nuclear pleomorphism. Occasional tumor cells were seen in association with dense amorphous material. Histologic examination of the excised specimen showed features of the so-called "sarcomatoid" chordoma which consisted of prominent foci of mitotically inactive spindle and pleomorphic cells, in addition to the conventional chordoma areas. An osteosarcoma-like pattern of probably metaplastic nature was also seen within the tumor. Immunohistochemical study showed that most tumor cells expressed cytokeratins. Ultrastructural examination revealed the characteristic rough endoplasmic reticulum-mitochondria complexes. While there are many spindle and pleomorphic cells seen in crush preparations, the distinction from other true high-grade malignancies is important. Recognition of these "pseudoanaplastic" cytologic features also helps to expand the morphologic spectrum of chordoma.